


Wyrm's Kiss

by Joths_Dump



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Anal Sex, Aphrodisiacs, Blow Jobs, Bottom Seteth, Bottoming from the Top, Gay Sex, Hand Jobs, Love Confessions, M/M, Not Beta Read, Plot What Plot/Porn Without Plot, Post-Timeskip | War Phase (Fire Emblem: Three Houses), Spoilers, Spoilers for Seteth and Flayn, byleth isn't the one who gives seteth the aphrodisiac, masochistic seteth, sex under the influence, virginal byleth
Language: English
Status: Completed
Published: 2020-04-10
Updated: 2020-05-12
Packaged: 2021-03-02 04:33:58
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 6
Words: 7,934
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23569132
Author URL: https://archiveofourown.org/users/Joths_Dump/pseuds/Joths_Dump
Summary: Seteth accidentally consumes an aphrodisiac. He seeks Byleth for treatment.I saw a post on twitter by user @44kage.Decided I wanted to take on the challenge.I have never written sex before so please go easy on me.
Relationships: My Unit | Byleth/Seteth
Comments: 4
Kudos: 54





	1. How it started

Up until now, Seteth’s Sunday had been like many others since Byleth returned. He woke up as soon as the Sun rose. He fixed his bed. Put on his cassock. Ate a small meal. Woke up Flayn and made sure she was ready for the day. Checked on the monastery guards for any new reports. Made sure residents were getting their fair share at the cafeteria. Lead a morning prayer at the Cathedral. Peaked in on the knights and former students in the training hall. Gathered any paperwork he or Byleth would need to fill out by the end of the week. Checked the marketplace for new goods and to make sure there were no shady transactions. He even went to the infirmary to see how the patients were fairing. 

Unfortunately, this was his first mistake.

Manuela was there as expected. So too was Hanneman, though this wasn’t unusual since the war began. Byleth had requested him to use any knowledge of biology he gathered while researching Crests to use. The three conversed; about patients, the war effort, supplies, rumors, and how they were holding up. Trouble arouse when it reached noon.

“How about we share lunch?” Manuela asked. “I managed to snatch a special ingredient for tea that I would love to share with the two of you?”

“That would be nice. We can continue our conversation as we eat.” Hanneman added.

Seteth had no plans for lunch himself. He was allowing Flayn space, and Byleth hadn’t sent him an invitation today. So, he agreed.

They met in the gardens. The had roast pheasant. It was nice. What wasn’t so nice was Manuela’s tea. Hanneman took a sip first. He narrowed his eyes and wrinkled his brow. “This is… certainly different.”  
Seteth was not deterred by Hanneman’s response. He took a sip; it was cloyingly bittersweet and ignited his throat and sinuses. It was somewhat familiar, nostalgic even. He continued to enjoy it.  
“Manuela… may I inquire what you used to prepare this tea?” asked Hanneman. 

“Isn’t it great!” she happily stated before taking another drink. “It’s Wyrm’s Kiss.”

Fuck. Seteth almost gagged on his tea. Why. Why did it have to be Wyrm’s Kiss?

“Manuela, are you joking?” Hanneman interrogated her. “Are you really trying to feed us a well-known aphrodisiac?”

“Not at all.” Manuela pouted. “That’s just an old-wives tale. There is no evidence to prove it.” She than began to mumble, “Trust me I’ve tested it out myself.”  
Both Seteth and Hanneman let out grief ridden sighs. Hanneman began to argue with Manuela … again. It was true that the plant had no such effects, on humans. It did however, succeed in stimulating Nabateans. Such as Seteth.

In truth the plant was popular with the Zanado population and while most knowledge of the Children of the Goddess was lost to the human population, some things persisted as rumors and myths.  
Dread had knotted in Seteth’s gut. He knew that as soon as it settled in his stomach the disaster would begin. He knew from experience after all. Before Garreg Mach, before the war with Agartha, before he lost his family, when he and his soon to be wife were happy and playful. But she wasn’t hear anymore. He would have to suffer this alone. 

Or would he? Seteth let out a sigh and excused himself. “If we’re done here, I have some work I need to catch up to,” he boldly lied. 

“Oh yes. Hope I didn’t ruin your meal,” Manuela apologized.

“Not at all,” Seteth lied while giving a phony smile.

He left the gardens. He snuck over to his bedroom, smuggling some water, food, towels, and weapon oil. He then began to ponder. Who could he trust to… treat him? Not Manuela clearly, she was to careless. Not Hanneman, he was to inquisitive. Additionally, they both knew he had consumed the Wyrm’s Kiss. They might suspect something of him. Or worse, seeing his reaction might trigger the placebo effect.

Not Catherine, she was too rowdy and might spill the beans. Not Shamir, she would just laugh at him. None of the other nights, that could be seen as an abuse of his authority.  
He needed someone he trusted and who trusted him back. Someone who would not weaponize his secrets. Someone kind and thoughtful. Someone like Byleth.


	2. Lucky Chance

**Summary for the Chapter:**

> Eager virgin slash fic fan Byleth meet sexed up Seteth.

Byleth had just finished his lunch. Well, his third lunch. He was always glad to share a meal with his former students and colleagues, but for some reason he was never allowed to invite more than two people at a time during lunch. But he didn’t mind, he could easily burn the calories by doing some sort of intense physical activity. Today he figured, he could polish his weapon skills. But who should he seek out first?

As he was walking into the gardens, someone called for him. “By- oof,” unfortunately Byleth did not notice in time and collided face first into the man’s chest.  
“Oo-oops,” Byleth apologized. He blushed a little at his mistake. He blushed even harder when he realized it was Seteth. 

Seteth sweet, doting, easily flustered, strong, reliable, and handsome Seteth. The man who was harsh on him at first (justifiably). The man who held tremendous love for his daughter. The man who took over Byleth’s duties in his time of morning. A force to be reckoned with on the battlefield, but with a weapon and on wyverns back, contrary to his stuffy mage-like appearance. Once Rhea’s assistant and now his own. Who wouldn’t be head over heels for him?

But there was something… odd. He was flushed and sweaty. Seteth was usually so composed, what could be wrong?

“Sorry Seteth.” Byleth apologized. “Did you need me for something?”

“Y-yes,” stammered Seteth. “However, it may require a lot of your free time.”

“That’s not a problem.” Not for you anyway, thought Byleth.

“Thank you… so… much.” Seteth wasn’t breathing normally, and the flush in his face was getting worse.

“Are you okay?” 

“YES!” shouted Seteth. It shocked Byleth’s eyes wide open and earned the concerned stares of more than a few people passing by. “I’m sorry, I just…” he let out a heavy and warm sigh. It almost seemed like… No, Byleth must have been imagining things. “I need you to help me with something… in my bedroom.”

Byleth was awestruck. Seteth’s BEDROOM! Not his office. HIS BEDROOM!  
“YES!” now it was Byleth’s turn to shout. Seteth looked flustered and eager.

“Thank you…” Seteth guided Byleth into the central building of the monastery. Up the stairs once, then twice. Up to the third floor where only the quarters of important members of Garreg Mach could be found. The whole time Seteth was rushing the two of them. 

Byleth was still confused about the situation. Why was Seteth behaving so odd? Why did he seem so feverish? What could possibly be the problem in his room? Maybe Cyril accidentally put a flower Seteth was allergic to in his room?

When they reached the door to Seteth’s room Seteth was desperately fumbling in his pockets for the key. He ungracefully tried to force his key into the lock to no avail. Byleth grabbed his hand and gently removed the key from it. Weird, definitely weird. He then carefully put the key in and unlocked the door.

“Mmmmm,” Seteth moaned. MOANED!? 

“What the…” Byleth thought to himself.

Once the door opened to the dimly lit room, Seteth pulled Byleth in by the wrist. He stepped a few feet forward into the room and then stood still. Byleth took the time to take stock of the room.  
The room was… surprisingly sparse. Actually, it didn’t look much to different from a student’s dorm room. Some nicer looking blankets and rugs, and the bed was a bit larger (but so was Claude’s). It did make some sense as even Rhea’s room wasn’t all that fancy. Like possibly sister like possibly brother, Byleth thought. There weren’t any flowers like he hypothesized. But there was some food, water, towels, and… weapon oil? 

Somehow still oblivious to the situation, Byleth turned around to shut the door. “I don’t see the- MMPH!” Byleth was rudely interrupted as Seteth’s lips crashed into his own. Seteth’s lean but powerful arms blocked off both Byleth’s left and right, pinning him to the door. Byleth’s head was swimming.

“This can’t be real. THIS CAN’T BE REAL! If this is a dream, do not wake me up Sothis!” Byleth begged to the void within his mind.

“By-leth…” Seteth let out a heady sigh. It was warm and moist. “I need you.” 

“How- how so?” he had an inkling of an idea, but he still was uncertain.

“Help me…” Seteth moaned again. “Help me feel better,” he begged.

“Do you, want to make out?” Byleth was still in denial.

Seteth was furiously unbuttoning his shirt. He practically tore of the last few buttons. He bore his chest to Byleth. It was dusted with fine green hairs, perky and erect pink nipples, and slick with sweat. It was a fine form suitable of a man who deftly dispatched foes with lances and axes.

“I want you to fuck me.” He demanded.

“What.”

“I NEED YOU TO FUCK ME,” he asserted.

Byleth squealed in an undignified manner through his tightly closed lips. Seteth wanted- no, NEEDED sex with him? Byleth couldn’t turn him down.

But wait… Byleth is a virgin. The only things he knows about sex are a few documents he shared with the book club. The one that meets up at night in his dorm room. The one with Sylvain in place of Ingrid. What did he say when Bernie asked for writing tips? Oh right, “pretty boys are by design meant to have a dick in them.”

“Do you want to put your penis in me?” Byleth muttered.

Seteth groaned. Byleth leapt in place a bit.

“No…no… you need to put your dick, in me!”

Byleth squealed again.

**Notes for the Chapter:**

> There are two book clubs. The official one with Bernadetta, Ignatz, Ashe, Flayn, Yuri, and Ingrid. And the other one that has Sylvain instead of Ingrid. Ashe and Yuri gave Sylvain an ear-full for that statement by the way.
> 
> I love how Seteth looks like a priest and is a Secretary. But instead of being a spell caster he flies around and eviscerates peeps. 
> 
> I'm probably going to take a breather before continuing, I already wrote and posted two chapters in one day afterall.


	3. Not so Steady Start

**Summary for the Chapter:**

> Byleth engages in sex for the first time. Seteth is still very much under the effect of an intense aphrodisiac.  
> So it doesn't go as expected.

The decision was a bit difficult for Seteth, he had no experience with other men. Hardly with anyone that wasn’t his late wife. But if he didn’t pursue sexual satisfaction, these symptoms could last for a whole day.

As such Byleth’s eagerness helped assuage is fears. He immediately dove for his chest and groped. Seteth winced and moaned. Byleth’s eyes were sparkling with excitement. “This is good,” thought Seteth. Byleth brushed his still gloved hands through his chest hair. He flicked at Seteth’s nipples, causing him to shiver.

“Byleth~” Seteth moaned. “Could you please remove your gloves? Actually, how about all of your clothes?”

“Oh! Yes, yes I will!” he shouted. He excitedly began to pull off his clothes. First his gloves, then his boots. Byleth was so cute, and surprisingly clumsy.

Seteth began to wonder, “Byleth isn’t a virgin, right?” Was it right to ask him for this? However as deeply affected by the aphrodisiac was, Seteth decided it didn’t matter as long as he had someone inside him. 

Seteth began to take off the rest of his clothing too. He carelessly yanked off his boots and through them to the furthest corner from his bed. He pulled off his pants with a fair bit of difficulty and discomfort, as he was already pitching an impressive tent in his pants. He pulled off his circlet and placed it as gently he could in his desperation, on his desk.

Now that he was down to his small clothes, he turned back to face Byleth. Byleth was, Byleth was lovely. When Seteth first laid eyes on him all those years ago, dressed in such warm black clothing, he thought Byleth to be a practitioner of magic. Perhaps even dark magic, the kind that drives men mad. He was surprised to see what a swift and fierce swordsman he was. But without his clothes on it was clear why. He was lean and toned. He had surprisingly few scars, no natural blemishes, and what hair he did have was short and fine. 

Seteth approached him, eager to get his hands on him.

“Eep!” Byleth squeaked as Seteth grabbed his bicep. It flexed in his grasp, and Seteth began to lick his lips in anticipation. Byleth was once again awestruck. Seteth whipped off his small clothes to finally bear his full self to Byleth, letting his cock stand free. Byleth audibly gulped, and stared at it with his cherry red face.

He tugged at Byleths own underwear. “Come on.” He demanded.

Byleth held his breath and pulled down his garments, much more gently and sheepishly. He too was at full mast now. It was a good dick, though smaller than Seteth’s “lance.” Seteth didn’t mind, in fact he was happy. Even under the haze of lust he still felt like the implement he and his wife utilized was too large for him. “Wonderful. Just wonderful.”

“Th-thanks.” Byleth sputtered. “You’re pretty sexy yourself.” Seteth then guided him to the bed. Seteth sat at the edge of the bed.

“Oil.” He commanded. He then laid back, with his legs hanging over the edge.

“Right.” Byleth nodded and grabbed the bottle of weapons oil on his bedside table and brought it back to Seteth.

“I want you inside me.”

“Yes,” hissed Byleth. He popped open the bottle and spread some on his right. He took a deep breath, and brought it to Seteths hole. He poked at it. Not exactly sexy. 

“Stop teasing me!” Seteth huffed.

“Sorry,” Byleth than ruthlessly thrusted his index finger into Seteth.

“MMPHH!” that was unexpected.

“Sorry… I’ll be more careful now.” Byleth began to explore the Seteth’s warm sweet hole. He wasn’t as skilled as Seteth hoped. But it didn’t matter too much since the Wyrm’s Kiss made him loosen up more easily. “Can I put another in?”

“Quit playing games.” 

“Huh? “

“I’m good enough. Penetrate me.”

Byleth’s jaw dropped wide open. “Aren’t we going to-“

“No! I’m more than ready!” he demanded. 

“Oh, okay.” His voice wavered. He took a deep breath, held it in for a second, and exhaled. He grabbed his shaft, aligned the head, and held it up against Seteth’s hole.

“Hurry up.” Seteth drawled.

“Well aren’t you desperate.” Byleth teased. He pulled back just a little bit and then pushed in. He managed to get more than half his length in Seteth in one motion.

“Sweet Sothis!” Seteth cried. 

“I’m sorry, did I…”

“No, it’s fine,” the aphrodisiac told Seteth to comfort Byleth. 

“Okay just tell me if- mmmm,” as he spoke, he shifted a little inside Seteth’s hole. Seteth was enjoying the feeling and it seemed that Byleth was too. “Just tell me if I do anything you dislike, okay?”

Byleth had no right being this sweet with his dick almost all the way up Seteth’s ass. “Thank you By. Now could you please continue. Seteth was flushed from head to toe and dripping with sweat. He had a huge dopey grin on his face. Byleth was looming over him in awe. While Seteth’s arms were stretched high above his head, reaching up to the pillows and folded underneath his head, Byleth’s arms were pinned to both sides of Seteth and allowing no escape. Not that he would want to at this point.

“Alright… let’s do this,” Byleth announced with certainty. He began to rock his hips back and forth. Pulling back towards the entry and pushing back in towards Seteth’s core. Having Byleth’s dick inside him gave Seteth an odd sense of completion. Whereas before, his being (ass) felt empty, Byleth filled up that void. Though he worried with the way the plant made him loosen up, he nonetheless tightened around the cock as it dragged back and forth.

He was so gentle.

Maybe too gentle.

The flames inside within Seteth’s gut began to roar again. He desired more. MORE! He lifted his legs and grabbed Byleth’s back, pulling him closer. Byleth was drawn in, his cock drove all the way into Seteth’s hole. Down to the base, Seteth could feel the younger man’s balls smack against him. Byleth bent down closer to him. They were face to face and Seteth could feel his own cock sandwiched between them. This was much better.

“Harder. Faster” he begged.

“Yes,” Byleth panted. “Whatever you want.” Byleth slammed into Seteth with considerable force. Seteth loosed a joyous hum. Byleth didn’t stop there, he rammed into Seteth continuously with a similar vigor. 

Seteth was loving it. The pull of Byleth’s dick on his insides. The way Byleth’s abdomen rubbed against Seteth’s cock as it was smashed against his own abs. They way Byleth’s forehead brushed against his lips so he could kiss it. The way Byleth moaned when Seteth’s fingers clawed at his back. It was finally starting to pick up.

“Oh Byleth…” Seteth sung his praises. 

“Oh Seteth…” Byleth moaned. “Seteth. Seteth. Seteth.” He muttered again and again. Byleth dug his face into the crook of his neck. The rhythm of the thrusts became faster. He continued to sputter Seteth’s name. It was almost as if he were going to…

“SETETH!” he cried, spilling his cum into Seteth’s insides. Byleth groaned. His thrusting began to slow. Byleth sighed with exhaustion. Even worse, he began to lift off of Seteth and retreat from within him.

No no no no no! This would not do at all! “Not yet! Don’t pull out yet!” he pleaded.

Byleth stopped before leaving Seteth’s hole. He bent a little closer. His breath was warm and heavy, but dry. “Sorry.” He said meekly. His cheeks were red, and not just from the physical exertion.

“Just… stay a bit longer…” 

Byleth dug back in a little further. He was losing turgidity, but for now that would be enough. Seteth grabbed hold of his own cock and stroked. He stroked like he never stroked before. He hoped Byleth would get the hint.

“Let me… help.” Byleth grabbed Seteth’s cock with his right hand. He still had some traces of oil on it but his grip was tight. Oh, so tight. He slid his hand up and down yanked the skin of the cock along with it. He bent it onto Seteth’s abs and began to dig his knuckles into his gut. Faster and faster. Even faster than he had thrusted into Seteth’s hole. It was furious, oppressive, painful, and just what Seteth needed.

Seteth moaned loudly. Desperately. Almost… “Byleth…” there… “OH!” He splurted viscous white all over himself. How messy, he would have thought.

Byleth slowed his pace as he made sure Seteth’s cock was properly milked. Once no more was coming out, he eased his grasp. He then pulled out. He was in awe as he watched his own seed ooze out of Seteth’s hole.

They were both out of breath. Byleth looked over Seteth’s form. He brought himself back up straight and walked over to the bedside table. He grabbed a flask of water, took a hearty gulp, and then handed it to Seteth. The cool water sliding down Seteth’s throat was wonderful it helped him feel rehydrated. But… It did not quell the flames within.

Byleth had gone to grab a towel when Seteth shouted “STOP!” He was dazed and confused as he looked back at Seteth. 

Seteth was now on all fours on the bed. Ass in the air. Dick regaining turgidity. 

“I’m… We’re not done yet!”

Byleth just stared at him. As if still processing the command. He closed his eyes. Layed his left hand down on the corner of the table. And gripped it with a force comparable to Dimitri’s leaving the corner cracked.

“Anything for you!” he exclaimed with a huge dopey grin.

**Notes for the Chapter:**

> Byleth's only experience with sex, is reading slash fiction. Can't blame him for coming so soon. He has more experience with masturbating, though he's a bit rough.
> 
> The aphrodisiac is still going strong. Under normal circumstances Seteth would have taken it a lot slower, he would have chose mutual masturbation or rutting against each other for their first time. 
> 
> Something I failed to explain is that Wyrm's Kiss makes it difficult to satisfy oneself. Would not recommend consuming it without a partner and some free time.
> 
> Don't try to imitate anything that occurs in this fic. My only experience is with slash fic and doujin. And the circumstances are kind of messed up. Though both individuals are without ill intent.


	4. Unstoppable Affection

**Summary for the Chapter:**

> Byleth may be inexperienced but he's a real go getter and a people pleaser.

Byleth is in over his head and he knows it. But he cannot deny his dear Seteth. Even if he is extremely afraid that he’ll disappoint again.

(Seteth wasn’t actually disappointed, that was the Wyrm’s Kiss speaking. But Byleth doesn’t know that.)

He figures he needs to be bolder. Seteth is begging for him after-all. He chuckles, “What do you want me to do for you now?” He hesitated for a moment. “My dear?”

Seteth whimpered in delight. Nice. “You should…” he mumbled, “You should let me ride you.”

“Holy shit…” Byleth groaned. This is good. Real good. Because Byleth may not have to put in as much effort and not risk showing how inept he is at this. “I would love that.” He gave a coy wink; the kind Claude likes to make.

“Yes yes yes.” Seteth hissed. “Thank you so much.” He looked like he was going to tear up. Byleth felt like he had no right being this cute while begging to milk his cock again.  
Byleth starts to crawl on top of the bed. He notices the oil bottle; he had carelessly left it open on its side and some of the contents were spilling out on the comforter. He picks it up and apologizes. 

“Sorry… I was careless.”

Seteth grabbed him by the chin and pulled him into a kiss. He tasted bittersweet. “That doesn’t matter,” he assured Byleth. “All I care about is you.”  
Byleth just gazed into his eyes with intense longing. His own eyes were getting watery. Dammit. What finally changed? What had he done to be showered with such love and affection?

Seteth gently motioned Byleth to lay his back against the bed. But before he had fully laid himself flat against the mattress, he had an idea. “Hold on just one second.”  
Seteth moaned a pitiful and fussy moan. Byleth fluffed up the pillows and propped them up against the headboard. He then fell back against them; his upper torso was angled upward. He had a prideful smirk. “Well?”

Seteth tilted his head in confusion, like a perplexed dog. 

“You’ll figure it out soon enough.” Byleth claimed with utter confidence. He grabbed the bottle of oil again and began to spread it out on his hand.

“Hmph. I don’t need that.” Seteth pouted.

Byleth just stared at him with disbelief. He knew that the weapon’s oil dries out really quickly. As much as Byleth wanted to do whatever Seteth asked of him, he wasn’t a masochist. “Maybe you don’t but I do.” He began to apply it to his own penis.

Seteth got impatient. He leaned over and groped at Byleth’s chest. Byleth eyes grew wide. He rubbed circles around his nipples. Byleth groaned and stopped lubing his cock. He felt it was sufficiently covered anyway. Seteth brought his hands down to the small of Byleth’s back. He situated himself against Byleth’s left side. Seteth brought his head down to his navel and kissed it. Byleth hissed in pleasure. Seteth continued by dragging his tongue; agonizingly slowly up Byleth’s abdomen causing him to moan “Mmmmmm.“ Seteth then surrounded Byleth’s left nipple with his mouth.  
“OH!” Byleth shouted. Seteth suckled on his nipple, and it made By’s whole body tingle. His cock almost felt harder than when he had it in Seteth’s ass. Seteth lifted his head away; he gave By a warm smile, and immediately gave the same treatment to By’s right nipple.

“FUCK! OH FUCK!” Byleth was definitely harder now. “SETETH!” He started to pant and begged, “Please just ride on my penis already, dear!”  
Seteth complied and surrounded both of Byleth’s sides with his limbs. Byleth couldn’t help notice how their positions had swapped. He even clenched his own sphincter in anticipation. But Seteth hadn’t chaned his mind. He erected his back and put all his weight on his knees and shins. He shuffled forward; he was now closer to Byleth’s face. Especially his massive cock. Byleth opened his mouth and felt saliva drip down.

“Not this time, By.” Seteth commanded. Byleth closed his mouth and held a sad little frown on his face.

“Next time.” Byleth thought to himself.  
Seteth spread his legs out wide and began to shift back into a squat with his ass hovering above Byleth’s cock. If By’s heart could beat, he imagined it would sound like a hundred Thoron spells firing off in quick succession. Seteth’s ass got closer. Closer and closer… He finally enveloped the head of Byleth’s cock in one motion. Byleth couldn’t help but sigh in pleasure. He wasn’t going to be tired of this anytime soon. Seteth continued to slide down around Byleth’s length. He hesitated around three fourths of the way down. He inhaled deeply.

“Let me help,” Byleth grabbed Seteth’s hips and pulled him all the way down to Byleth’s base.

“OH!” Seteth cried. “…Oh.” He realized.

Told you!” Byleth gloated. He loosened his grip on Seteth’s hips.  
Seteth lifted himself up a little bit, and dropped back down again. He rose again, and dropped again. Again and again and again. Bouncing up and down, up and down. His cock was bouncing with him.

“Ahh-“ Byleth sighed. He could feel himself relaxing into the pillows. He was tempted to let Seteth take total control of the situation. But then he remembered his earlier mistake. So he tried to thrust up into Seteth just as Seteth was sliding back down.

“MMPPHH” Seteth grunted.

“YEAH! YOU LIKE THAT?” Byleth shouted triumphantly. Was he trying to get them caught?

Seteth wimpered like a dog. “Oh… Byleth…please keep it up.”

Byleth complied. He fervently thrust into Seteth’s ass again, immobilizing him with pleasure. “Mmmmmm-“ Seteth’s groan caused the heat in Byleth’s gut to flare. He continued to thrust and thrust and thrust. All Seteth could do was sit still and take it as precum leaked from the head of his cock.  
It made Bylethh go berserk. He grabbed Seteth’s cock with his right hand again and tightened his left grip on Seteth’s waste. He began to thrust and stroke in a chaotic unison.

“Ha…ha…” Seteth panted. His breath was heady and moist. Byleth didn’t let up. He kept pounding into Seteth’s hole while abusing his cock. Goddess By hoped he would come soon.

“BYLETH!” Seteth cried, spilling sticky white onto Byleth’s chest and nearly hitting his chin. Thank goodness. Seteth collapsed forward resting his head against Byleth’s and smearing his own cum across their chests.

“SETETH!” Byleth shouted. He released into Seteth’s ass once more but not nearly as much as he had before. Though that could not be discerned as it mixed with what was left behind.   
They sat there like that for a minute or so. Desperately trying to catch their breaths. Eventually Seteth managed to pull himself up off of Byleth. But as soon as his body was no longer looming over Byleth’s he collapsed into the mattress. He looked straight into Byleth’s eyes, both of their cheeks were stained with tears. “Thank you.”

Byleth’s eyes began to tear up again. “I love you.” 

Seteth’s whole face flushed bright pink. He coughed roughly. “R-really?”

Byleth grabbed Seteth’s hand and brought it to his lips, kissing it on the knuckles. “Yes. More than anyone else.  
He did it. He finally bore his heart and soul to Seteth. He could feel himself heat up with joy and anticipation. He stared into Seteth’s eyes with immense determination, more than he had ever shown to any foe. 

Seteth was flabbergasted. He mumbled something intelligible. Byleth just gazed into him with the warmth of the sun. Seteth closed his eyes and took a deep breath. He slowly released the air through his nose and responded, “I love you too.” His smile was warm and tender.

Byleth leaned his head in and kissed Seteth’s lips. It was far more chaste and laxer than the previous ones; it was a testament to Byleth’s want for not only Seteth’s body, but his whole being.  
The began to snuggle up into each other. Unperturbed by the mess they made of themselves. Byleth gently closed his eyes and drifted to sleep.

**Notes for the Chapter:**

> Originally I wasn't going to depict Byleth trying to thrust while being ridden. He was keep his lower body still and just work Seteth's length again. But I suddenly wrote it in and I didn't want to change it.  
> A couple of times I get fed up with writing their names out so much that I shorten Byleth to just By. I was going to fix it in editing but got tired. T_T  
> Next chapter should be the climax (heh) of the story. Seteth's head clears up a bit and he thinks about what will become of them.


	5. Interlude: What's going on?

**Summary for the Chapter:**

> Brief interlude before the end.  
> Flayn tries to find out what's going on. No sexy times. Kind of dramatic, sorry I got carried away.

Flayn searched high and low. She checked the fishing pond, the greenhouse, the dormitories, the dining hall, etcetera. She asked the clergy, the knights, the former students, her clubmates, the refugees, and the orphans. She could not find her Father or Byleth. 

She had heard from some of the staff that Seteth requested the rest of the day off, and that he was last seen outside the dining hall with Byleth. But that did not explain why they didn’t tell her anything. Seteth seldom makes sudden schedule changes without telling Flayn first. Nor would Byleth, at least not since he took on the role of archbishop.

She was afraid. Afraid that something related to their past was being kept from her. Afraid that once again she wouldn’t be there to help her family when they needed her most.

She was heading to her father’s office again when she bumped into Hanneman.

“Oh. Pardon me Flayn. I was lost in thought and hadn’t noticed you.” He gave a gentlemanly bow of apology.

“No need to worry, I’m perfectly fine.” She was just about to walk away when she realized she hadn’t asked Hanneman if he knew anything. “Hanneman, have you perchance seen my brother or the Professor lately?”

“No. I haven’t seen Seteth since…” his brow furrowed and he let out the sigh of disgust he always makes when Manuela disappoints him, “Not since lunch when Manuela served us that horrid tea.”  
Tea? “What kind of tea did she serve? Was it spiked with alcohol?”

“No, she used Wyrm’s Kiss.” 

A light turned on her head. Everything had finally come together; her father had accidentally ingested a powerful aphrodisiac and sought out Byleth for relief. That made perfect sense.  
“HOLY SHIT!” she thought to herself. Fortunately, to Hanneman she just looked confused with her eyes wide open and her brow crinkled.

“Ahh, so you have heard the rumors. There is no need to worry, there is no scientific basis for those stories.” He assured her, fully unaware for how wrong he was. 

“Oh…” she sputtered. “No, I already knew that.” She would never indulge how she did, but she did. “Well I’ll go check the greenhouse next. Thank you for help.” She held a wide smile and gave a little bow.

“No problem.”

She then discreetly fast walked to the stairs. She wasn’t going back down to the greenhouse. She checked to see that no one saw could see her, and then dashed up the stairs.  
The highest floor was the one place she hadn’t checked, but that was because virtually no one when up there during the day. Except for Cyril when he went to make sure Rhea’s room was in order for her return. Goddess bless his soul.

With that important detail, she could finally pin down where her father and Byleth had snuck off to. Fortunately, her initial worries were completely off the mark. But still… were those two really having sex? Had the two men’s relationship developed to the point that they could comfortably engage in such activities.It’s true that Seteth now full-heartedly trusted Byleth, and that the horrid effects of that accursed plant would persist much to long without help. It was also true that Byleth had a tendency to hang around Seteth; and was also found of elicit text regarding two men. Especially the kind that was based on the saints. 

Ugh. Did she really have to remember that? She’s glad that night she was able to encourage the rest of the After Dark Club to discuss a different story. It was still hard to justify why she was so embarrassed when she bumped into Byleth while he was sneaking a story about Cichol and the first emperor to his room. 

She stopped in front of her father’s room. Fortunately, she couldn’t hear anything coming from inside. She took a deep breath through her nose, held it for a second, and then gently exhaled through her mouth. She knocked on the door and then waited for 15 seconds. There was no response. She knocked again. Ten seconds later she heard some stumble and stomp around. The sound approached the door and slowly, carefully the door opened inward on the right. Just enough for Seteth to poke his head and shoulders through. His face was flushed red and sweaty. He was wearing his bathrobe with the belt haphazardly knotted together. His left ear was beginning to peak out of his hair before he quickly covered it back up. Flayn had the presence of mind to not try to peak in any further.

He was panting, his breath still smelled bittersweet; the aphrodisiac had not yet worn off. “Flayn… I can explain.”

“Your having sex with the professor.” Critical hit.

Seteth sputtered. He couldn’t look her straight in the eyes, “What makes you think-“

“Hanneman told me you drank Wyrm’s Kiss.” 

Seteth winced in response. “How do you know what that-“

“That doesn’t matter right now.” There was no way in hell she was going to have that discussion with her father now. “Why with Byleth?”

Seteth closed his eyelids tight. He loosed out a deep sigh and spoke, “He is the only person I am comfortable enough with to request help with this matter.”

A big goofy grin formed on Flayn’s face. “I am glad to know that you and the Professor have grown to care about each other so genuinely.  
Seteth reddened further. “Th- thanks.”

“But father, I know that the conditions will persist if you don’t treat them immediately,” she paused for a few seconds, “But do you not think that it may be questionable to engage in such activities under the influence of such a powerful compound?”

Seteth averted his gaze again. “He…he…” Seteth muttered the rest of the sentence under his breath.

“He what?”

“He doesn’t know.”

SOTHIS’ TITS! “HE DOESN’T KNOW?” her voice nearly rose to a shout. She could hear Byleth begin to stir from across the room.  
Seteth held up both his hands in a STOP gesture. “It’s not what you think…”

“What the hell do you-“

“He told me he loves me.”

“That doesn’t-“

“I told him I loved him too.” Flayn’s jaw nearly dropped to the floor. “And I think… No. I know I meant it.”  
She stood their frozen in place. Was this all for real? Was the bond between Seteth and Byleth more than just that of two colleagues who were unafraid to engage in casual sex. Had her father finally decided to build a new life? To move on from her mother and the tragedies of a millennium ago? So many thoughts were swimming through her head it was difficult to handle them all. She was both excited about the prospect, and apprehensive. She was elated to see her father finding new love, but she was also pained by it.

“Please Flayn, trust me. I’ll have this all sorted out in do time.” Seteth begged. 

“…” her eyes and mouth were shut tight. She reopened her eyes and sighed heavily. “Alright father, I trust you. Both of you.”

“Thank you. I’ll see you later.”

“Be careful okay?” 

“I will.” He retreated back inside and gently closed the door.

Flayn sighed again. It looked like she would have to stop any one from looking for them. She wondered how their lives would change from here on out. What would Rhea think of this when she came back? Would there be a scandal?  
Flayn decided that she should focus on the right now. She held her head up high and marched backstairs. Whatever may come, they would weather through it.

**Notes for the Chapter:**

> The last couple of weeks have been difficult. But I was finally able to continue this work! Albeit not in the way I promised. Don't worry the next chapter should be the real final chapter. Then I can finally work on new fics!
> 
> Flayn is one of my faves in 3H and I would have liked if she got more play in the main plot, it could have been real interesting. Oh well.
> 
> Sorry if it got to moody.


	6. Seal it with a "Kiss"

**Summary for the Chapter:**

> It's time to close out this story. With a "kiss."
> 
> aka, a blow job.

Seteth gently sat down on the bed. He gazed at Byleth who had his head smushed between the mattress and a pillow. He was probably trying to block out the sound of Flayn and Seteth’s conversation. Seteth couldn’t help but smile like a big dope. He truly did love this man. He would like to lay back down and go back to sleep. But he had too much to do; he had to clean their mess, get themselves to the baths, talk about their future… But he still needs to take care of the problem that started it all.

He carefully pulls the pillow off of By’s head. “Byleth, now is not the time to sleep dear.”

Byleth grunted, “Ughh… “ Byleth sat up blinking his eyes open. Once his sight was clear, he turned to face Seteth. He couldn’t but blush when he remembered where he was. And once his eyes wandered down his to Seteth’s groin he only got redder. “Your hard again?” 

Yes, Seteth was once again suffering a raging stiffy. “I-I… I’m not quite myself. Too be honest.” Seteth covered his face with both hands in embarrassment.

Byleth just awkwardly stared at Seteth for a few minutes… actually, just a few seconds. But Seteth’s embarrassment made it feel like an eternity. “Is this my fault?” Byleth inquired with a sad tone of self-dissatisfaction. 

Seteth nodded his head side to side. “No. I guess you could say I’m… under the influence?” Seteth’s half-bake explanation only seemed to confuse By even more.

“You’re drunk?” he had a sad little pout as he asked this.

“Ah no… it’s a drug.” Seteth muttered. “I’m sorry.”

Byleth just stared into space silently. It painfully reminded Seteth of when he had first come to the monastery. Byleth took a deep breath and spoke, no, choked “Do you really love me?” 

Seteth gazed directly into Byleth’s eyes with intent and determination. He brushed the hair on the side of his head back and tucked it behind his ears. Byleth was dumbfounded, he had never even realized that he had yet to glimpse the entirety of Seteth’s ears. He certainly had not expected it to be so familiarly elongated and sharp. Seteth gently grabbed Byleth’s left hand with his right and pulled it to his right cheek. “I do love you Byleth.” This time, there was no embarrassment or shame in his tone. Only trust, love, and confidence in a future together.

Byleth’s eyes flooded, but with joyous tears. He brought both hands to Seteth’s cheeks and caressed them. Seteth in turn, wrapped his around Byleth’s waist and brought them closer together. They pressed their foreheads together gently, and enjoyed the serenity of the moment. However, this calm was broken as Byleth’s traitorous hands worked their way up Seteth’s head. They pinched the tips of Seteth’s ears. He bit his lower lip and made a muffled cry. 

Byleth quickly apologized “Sorry, sorry I didn’t mean to…”

“Good…” Seteth moaned.

“Ah. You’ve really got it bad huh?” now he was just being cheeky.

“Yes, but you’ve made it a lot better.” Seteth chimed.

“So how are we supposed to fix this?”

“As I said, you have helped relieve most of the worst symptoms. I will be back to normal in a few hours.” Seteth’s expression then became a bit dour. “We should clean up. We can’t risk anyone finding out about this… little arrangement. We have neglected are duties after all.”  
Byleth pouted. “Harrumph.” Seteth slipped off the bed and stood up straight. He bent over the side table to grab some things. Byleth couldn’t help but think Seteth looked goofy trying to act normal with his monster dong rock hard and on full display. But it was also kind of erotic. It was then he had an idea. He hung his own legs over the bed and said, “Come over here real quick babe.”

“Babe?” Seteth was in disbelief. Nonetheless he put down the towel he grabbed and walked back to Byleth. He looked directly at his cock and turned red as a tomato.

By tilted his head and held a smug grin, “Next time~?” he chuckled.

“Yes, I will be fine on my own for tonight. We can do this again some other time.”

“No no.” Byleth had a teasing lilt to his voice. “Next time.”

Seteth had only just barely comprehended what By meant when his arms lunged around Seteth grabbing at his ass and pulling him close. He came dangerlously close to stabbing Byleth in the face. Byleth was unflinching, he licked the head of Seteth’s cock from the underside over the slit. It made Seteth shiver and shake.

“OHHHH!” Seteth cried. “Byleth! You are insatiable!” he admonished him for his lasciviousness.

Byleth just snickered. “It wouldn’t do you any good to stay like this any longer.” He rapidly stood up, and wrapped his arms around Seteth’s kiss. He gave Seteth a lewd kiss, and a slight taste of his own residual cum. Gross. But kind of hot.

Seteth pulled back for air, “Byleth you don’t have to worry about me. I’ll be fi_” He was cut off.

“I just think we should consummate our relation.” Byleth stated in an oh so matter of fact manner. With a coy wink for added flavor. It was then that he quickly spun them around, and practically tossed Seteth back halfway on to the bed. 

“Woah…” was all Seteth could muster.

“Come on now.” Byleth wildly gestured towards the pillows.  
Seteth did as he was told, yet still made a fuss. Byleth crawled back onto the bed as well and helped Seteth ease himself back on the pillows.

“Now sit back as I take care of you my dear.” Byleth spoke with a faux aristocratic tone.

“By…” Seteth muttered. “I appreciate this but you don’t need to push yourself so hard.”

“Pft. Come now, we have been putting up with so much lately. Besides…” Byleth gently grasped Seteth’s coke and rubbed the sensitive slit, “You still need my help.”

Seteth couldn’t deny that his body was not yet free of the aphrodisiac. Nor could he deny that even without the mind-altering effects, he still craved Byleth’s warm and wet mouth wrapped around his cock. “Yeah… I do.” Seteth shamefully admitted. He leaned back into the pillows once again laying himself bare to Byleth.

Byleth grinned warmly. He slowly lowered his head to Seteth’s cock. He brushed his own hair back to keep it out of the way. Slowly he shaped his lips in a wide O, driving Seteth made with impatience. He looked up towards Seteth’s face one more time, to see his flushed faced. By wiggled his brow and then surrounded the head of Seteth’s cock with his lips. 

“Ohhhh,” Seteth moaned. “By…leth!” he gasped when By’s mouth slid further down his cock. 

As it reached his uvula he hesitated. Byleth mustered his courage and lust, and took little more than half of Seteth’s cock into his throat. He reflexively grunted and moaned in a less pleasant manner. 

“By…” Seteth gasped for air, “By!” 

Byleth slipped off the cock, leaving a thread of saliva trailing behind. “Ith vine.” He slurred with a huge grin on his flushed face.

Seteth leaned forward, cupped Byleth’s left cheek, and stroked it with his thumb. “Please. Don’t push yourself.” Ever the worrywart. 

Byleth nodded his head in agreement. He cautiously popped back on. He grasped onto Seteth’s thighs. He groped and massaged Seteth’s thighs as slid up and down. He dragged his tongue along the enlarged underside of the penis. The warmth and moisture were utter bliss to Seteth. 

Byleth picked up the momentum of his rhythm. Up and down, faster and faster. Seteth cried and thrust his groin up a bit, fortunately when Byleth was pulling back.

“Hey, what happened to being careful?”

“Forgive me. My desire got the better of me.” 

“Hmph” Byleth dug his fingers deep into Seteth’s flesh, drawing a hiss from his lips. Byleth dipped his head down to Seteth’s balls. He gently nipped at the scrotum.

“Mmph!” grunted Seteth, though it sounded oddly pleased.

“My my, what a masochist.” Byleth teased. Before Seteth could even get a word in Byleth swallowed more of Seteth’s cock again. Without loosening his grip. 

Byleth continued to taste and tease Seteth’s cock granting him no relief. Seteth desperately wanted to thrust again and thoroughly throat fuck his pretty little head. But his concern won, and Seteth was forced to lie back. He clenched tightly onto the sheets below him and cried and moaned.

“By…By…By…” he chanted religiously. Byleth only continued to speed up, his motions were becoming more excited and frantic.

“By… BY! I’m going to… I’m going to!” Seteth nearly screamed. But Byleth wasn’t slowing down. Seteth in response leaned forward and grabbed Byleth by his hair and yanked him off his cock. He closed his eyes and shot a sticky-sweet load of white cum onto Byleth’s face. Byleth kept his mouth open and tried to catch as much as he could, but much of it was smeared across his nose and cheeks. By fervently palmed at his own erection. He growled and moaned viciously, until at last he silently cried out. He had little cum to give at this point, but the climax wasn’t any less strong. It made Byleth’s whole body tremble and shake.

They remained largely still, panting like dogs. Seteth opened his eyes again and admired his handy work. Byleth’s face was stained white with his cum and his lips were swollen and red. Byleth stared back out Seteth, exhausted and teary eyed. But utterly and hopelessly infatuated with Seteth’s grand smile of utter delight and satisfaction. Both of them were warm and glowing.

But all good things must come to an end. “Let me clean us up.” Said Seteth.

Byleth was wiping off the extra cum off his face and onto the mattress. “Shouldn’t I be the one who does that? After all I’m the one who took control.”

“Yes, and I sat back as you did so. All the more reason for me to put in the work as you allow yourself to rest.” Seteth said assertively. Geez it was almost like a lecture…

“Okay okay…” Byleth admitted defeat. He scrambled up to the pillows and laid back down next to Seteth. Seteth reached over and grabbed a towel and another water flask. He dabbed a little water onto the towel, and begun to wipe Byleth clean.

This moment together was warm and intimate. Unlike their previous acts, the aftercare only aroused the hearts. The bathed in the silence and their shared affection, radiating like the sun rays.  
After Seteth was finished wiping them both down, he took a swig of water from the flask. He then handed it over to Byleth.

“Hmm… I’m not sure I’m ready to let go of your taste.” Byleth chirped.

“Come now.” Seteth huffed. His expression turned into a grin, “You’ll just have to wait until next time!”

They both giggled. 

“You don’t expect us to leave and wash up do you?” asked Byleth.

Seteth looked down and sighed. He wouldn’t answer.

“You’ve brought plenty of food and water. And we don’t have to worry about the sheets just yet. So why don’t we lay back down for a while?” 

“But By…” Seteth was interrupted when By grabbed his shoulder and placed his index finger to his lips.

“You work to hard. WE work to hard.” He claimed. “We deserve the respite. And if someone finds out about are little tryst… Let them.” Byleth winked. “I was already thinking of proposing to you after the war is over anyway.”

The red in Seteth’s face spread from his cheeks to the tips of his long-refined ears. 

Byleth chuckled. He wrapped both of his arms around Seteth’s shoulders. The two men pressed their foreheads up against each other once more. Byleth spoke once more, “Let’s enjoy our rest, my dear.”

Seteth grinned, “Certainly.” The two of them pulled back the covers and descended back into the pillows. Their bodies intertwined and they quickly drifted back into their much deserved sleep.

**Notes for the Chapter:**

> These last few chapters have come out a lot slower than the first few. Stuff happened. Sorry.  
> Nonetheless I'm glad to have worked on this. Even though I feel like it was pretty dumb of me to put in so much detail in the set-up and in Byleth and Seteth's relation. But isn't it kind of nice? To add a little romance into the mix? 
> 
> Can't say for certain what I'm going to post next. But I have a bunch of ideas. Including some long fic. Expect more Dimidue than other ships though, it's my fave. i would also like to revisit the setting of this fic. Not for kinks or sex but just for fun! Might make something funny about the book-clubs. You never know!
> 
> Thank you all again for reading my work.

**Author's Note:**

> "i want seteth aphrodisiac shenanigans dub con PLEASE please." - twitter user @44kage 
> 
> Don't worry Manuela did not try the aphrodisiac on someone else. She also wasn't trying to drug Seteth or Hanneman either. She liked the taste and wanted to share it with her colleagues. There is no way she would have known it actually would work on Seteth.
> 
> Also I haven't figured out what kind of sex acts the couple are going to get up too, that's why I haven't tagged any yet.
> 
> Edit: I have now!


End file.
